【摘要】 本文介绍了球铁奥氏体化过程以及随加热温度和保温时间的不同,球铁奥氏体平均含碳量的变化。结果表明,球铁奥氏体化过程完成相当快。温度升高,转变加快。奥氏体转变刚结束时,奥氏体(基体)平均含碳量较低(约0.55～0.65%),保温使基体继续增碳,直至饱和。碳在奥氏体中的饱和含量随奥氏体化温度升高而升高。钼减缓碳在奥氏体中的扩散,但增加碳的固溶度,铜则同时增加碳在奥氏体中的扩散及固溶度。试验表明,奥氏体化温度较低时,奥氏体首先在共晶团晶界形核,奥氏体化温度较高以及加热速度很快时,则优先在石墨球周围形核。更多还原

【Abstract】 The austenitizing process and the variation of average carbon content in austenite with different austenitizing temperature and holding time in ductile iron were studied. It was shown that the austenitic transformation is accelerated by raising the austenitizing temperature. At the end of transformation, the average carbon content in the austenite is about 0.55～0.65% and increases to the saturated solubility as holding proceeds. By raising the austenitizing temperature, the solubility of carbon in the austenite is increased. It is found that molybdenum retards the diffusion of carbon, but increases its solubility. However, copper enhances both the diffusion and solubility of carbon. It is also found that when the austenitizing temperature is low, the austeniti is firstly nucleated on the boundaries of the eutectic grains and when the austenitizing temperature is higher and the heating rate is more rapid, the austenite is preferentially nucleated around the graphite globes.更多还原